Arterial blockages caused by the build up of plaque in the arteries of a patient can have grave consequences. Specifically, the build up of plaque in arteries can reduce and eventually block the flow of blood through the affected vessel. When blood flow is reduced in the coronary arteries, the heart muscle can become deprived of oxygen, and the patient is often prone to suffer angina. In severe cases of coronary artery blockage, the patient can suffer a heart attack.
Fortunately, many modern surgical techniques, such as percutaneous transluminal coronary angioplasty (PTCA), have been developed to alleviate the stenoses that are formed when plaque builds up in a patient's arteries. These procedures use a balloon angioplasty device to relieve arterial stenoses by compression of the stenosis. In angioplasty surgery, the balloon of a balloon catheter is initially attached to a catheter tube in a deflated configuration. The balloon is then inserted into and advanced through the vasculature of the patient until the balloon is positioned across the stenosis requiring treatment. Once the balloon has been properly positioned, fluid is infused into the balloon. As the balloon expands, it dilates the lumen of the artery and compresses the plaque. The balloon is subsequently deflated and, once in its deflated configuration, it is either withdrawn from the artery or placed across another stenosis, to restore normal blood flow through the artery.
A particular problem associated with an angioplasty procedure exists during the deflation stage of the balloon, prior to its removal from the artery. In greater detail, it is desirable that the balloon be deflated as tightly as practicable to facilitate its removal from the arterial passageways. Specifically, it is desirable to have the balloon collapse evenly and compactly during balloon deflation. Once deflated, the balloon catheter must often travel through tortuous passageways and it is, therefore, desirable to have the balloon deflate uniformly into a predictable configuration. If the balloon fails to deflate in a uniform manner, an irregular bulge in the balloon may cause difficulties in withdrawing the balloon catheter from the artery.
Although conventional percutaneous transluminal coronary angioplasty (PTCA) procedures have been somewhat effective in treating coronary artery disease, cutting balloons can also be an effective treatment option for the revascularization of both coronary and peripheral vessels. The cutting balloon mechanism is unique in that the balloon pressure is distributed over one or more blades (i.e. microtomes). The blade(s) function as stress concentrators and cut initiators in PTCA atherectomy procedures. In some cases, PTCA atherectomy procedures may be effective in reducing vessel recoil and vessel injury and in lowering the rate of restenosis, as compared to conventional PTCA procedures.
The atherotome blades used in cutting balloons are extremely sharp (e.g. three to five times sharper than a conventional scalpel). It is desirable that the blades do not tear, cut or perforate the inflation balloon during assembly of the cutting balloon, handling or during clinical use. In addition to balloon perforation concerns, an inadvertent incising of tissue as the cutting balloon is being moved through the vasculature is also undesirable.
Along these lines, a device having a blade-like structure which is described as a “parting edge” which is shielded within the pleats of an expandable clover leaf shaped tube is disclosed by Shiber in U.S. Patent application publication No. 2002/0151924, filed Oct. 17, 2002 and entitled “Clover Leaf Shaped Tubular Medical Device”. However, the clover leaf design disclosed by Shiber does not necessarily protect the relatively fragile balloon from the “parting edges.” This is because the “parting edges” are located within the pleats of the balloon leaving portions of the balloon exposed to the “parting edges” when the device is twisted, turned and bent through the curved vasculature of a patient.
In addition to the conventional PTCA treatments and PTCA atherectomy procedures described above, it is sometimes desirable to inject a medicament into a vessel wall. For example, U.S. Pat. No. 6,102,904 which issued to Vigil et al. on Aug. 15, 2000 for an invention entitled “Device for Injecting Fluid into a Wall of a Blood Vessel,” and which is assigned to the same assignee as the present invention, discloses such a device. As disclosed in Vigil '904, the device includes an inflatable balloon that is mounted on a catheter and a plurality of injectors that extend outwardly from the balloon. A fluid passageway is provided to place each injector in fluid communication with a fluid source. During use of the device, the balloon is first positioned in a vessel proximate the treatment area. Next, the balloon is inflated to embed the injectors into the vessel wall. Subsequently, fluid from the fluid source is introduced into the fluid passageway and through the dispensers into the treatment area. Like the atherotome blades described above, it is desirable that the injectors do not tear, cut or perforate the inflation balloon during assembly of the cutting balloon, handling or during clinical use.
In light of the above, the present invention is directed to unique devices and methods for refolding the balloon of a balloon catheter. In addition, the present invention is directed to balloon refolding devices and corresponding methods of use which are relatively simple to implement and comparatively cost effective.